Amination of alkylbromides



April 3, 1968 G. R. WYNESS ETAL 3,379,764

AMINATION OF ALKYLBROMIDES Filed Sept. 1, 1965 RN 00 18 H EC LA 47 m mPm -6 EH mm l. 5 MM RA E PW -4 O U N 3 m MO T p O O O O O O O O 5 O 5 O5 3 2 2 I I E IZMEIAE mmmmwmo Z. wm3h mumimh TIME IN MINUTES m FM l mmFA 5 0% r) R 7 N mw R 6 N MN RM 5 EA H W 4 T A B 3 2 E M N T 2 F T f. OO 0 w w a m m m w 0 TIME IN MINUTES [NVEVTORS glen R. Wyness ougIos W.Jensen W CIA/di ATTORNEYS United States Patent Oflice 3,379,764 PatentedApr. 23, 1968 3,379,764 AMINATION F ALKYLBRUMRDES Glen R. Wyness,Cincinnati, and Douglas W. Jensen, Greenhiils, Qhio, assignors to TheProcter & Gamble Company, Cincinnati, Ohio, a corporation of Dhio FiledSept. 1, 1965, Ser. No. 484,172 7 Claims. (Cl. 260583) ABSTRACT OF THEDISCLOSURE Process for preparing trialkylamines from a mixture ofalkylbromides containing alkyl groups of from to 20 carbon atoms,dialkylamines containing from 1 to 3 carbon atoms, and water, the molarratio of dialkylamine to alkylbromides being in excess of about 8 :1 byreacting the alkylbromides with the dialkylamines for 2 to 7 minutes ata temperature of from 100 F. to 190 F. and thereafter heating thereaction product to a temperature of from 275 F. to 375 F. for from 4.5to 12 minutes.

This invention relates to a process for the preparation of tertiaryamines by aminating alkylbromides.

One outgrowth of the increased use of amine oxides as syntheticdetergents has been the need in the detergent industry to find animproved method of preparing a relatively pure oxidizable tertiary amineproduct. Such amines can be produced by aminating an alkylbromide.

An important source of alkylhalides is via a reaction between alphaolefin raw materials and, either, a halogen or a halide acid. By thisreaction, the a-olefins are converted to both primary alkylhalide, e.g.,l-bromoalkane, and secondary alkylhalide or internal halide, e.g.,2-bromoalkane. With free radical addition processes, about 90% to 95% ofan essentially straight chain a-olefin raw material can be converted toprimary sraight chain alkylhalides, e.g., alkylbromides. a-Olefin rawmaterials also contain small amounts of branched chain olefins. Thesebranched chain olefins are converted to branched chain alkylbromides bya free radical bromination reaction. In addition, the reaction productwill also contain small amounts, i.e., about 5% of internal bromides.

Processes for aminating mixtures of alkylbromides of the type justdescribed presented several problems. One of the most serious was thatsubstantial quantities of quaternary ammonium compounds were formedalong with the desired tertiary amine compounds. The quaternary ammoniumcompounds constitute impurities in the end product when it is to be usedin the preparation of detergents, e.g., the amine oxide. The formationof the quaternary ammonium compounds is costly, yet these compounds areinert components in the amine oxide synthetic detergent. It can readilybe appreciated that the formation of these quaternary ammonium compoundsis undesirable and if possible should be avoided. In some cases, whenthe quaternary level becomes too great from the practice of knownprocesses, the formulator has no choice but to separate the quaternaryammonium compounds from the tertiary amines at considerable expense.Additionally, it has been found that branched chain bromides andsecondary bromides require an inordinately long reaction time tocompletely react with the various dialkylamines during an aminationreaction at the lower temperatures at which the primary alkylbromidesreact rapidly. If higher temperatures are utilized to shorten thereaction time, undesired ammonium compounds are formed. Regeneration ofolefins from the secondary alkylbromides is also often a problem.

Accordingly, it is a primary object of this invention to provide aprocess for preparing tertiary amines, i.e., trialkyl amines, byaminating alkylbromides comprising major portions of primaryalkylbromides and minor portions of branched chain and secondarybromides, which process reduces or eliminates problems ordinarilyconnected with such amination. It is a further object of this inventionto provide a process of preparing tertiary amines which is rapid andcontinuous and which results in minimal regeneration of a-oleiins andquaternary ammonium compound formation. Another object of this inventionis to provide a process as described above which insures substantialcompleteness of the reaction.

Still further objects and the entire scope of applicability of thepresent invention will become apparent from the detailed descriptiongiven hereinafter. It should be understood, however, that the detaileddescription and specific examples, while indicating preferredembodiments of the invention, are given by way of illustration onlysince various changes and modifications within the spirit and scope ofthe invention will become apparent to those skilled in the art.

It has now been discovered that the foregoing objects of the presentinvention for preparing a trialkylamine are attained by a procescomprising the steps of (1) Preparing a reaction mixture containing analkylbromide, said alkylbromide being comprised of a major portion ofstraight chain primary alkylbromides and a minor portion of straightchain secondary alkylbromides and branched chain primary alkylbromides,wherein the alkyl group of said alkylbromides contains from about 10 toabout 20 carbon atoms; and a dialkylamine-water solution comprising adialkylamine wherein the alkyl groups contain from 1 to about 3 carbonatoms; said dialkylamine-Water solution containing from about 5% toabout 20% water by weight; the molar ratio of said dialkylamine to saidalkylbromide in said reaction mixture being in excess of about 8: 1;

(2) Reacting said alkylbromide with said dialkylamine for from about 2to about 7 minutes at a temperature of from about 100 F. to about 190 F.and under sufficient pressure to maintain said dialkylamine in aliquified state to form a reaction product;

(3) Thereafter heating said reaction product to a temperature of fromabout 275 F. to about 375 F. for from about 4.5 to about 12 minutes andunder sufiicient pressure to maintain said dialkylamine in a liquifiedstate.

FIGURE 1 and FIGURE 2 are drawings showing time/temperature profilescharacteristic of the amination reaction of the present invention.

In the first step of this invention, a reaction mixture comprising analkylbromide, a dialkylamine and Water is prepared.

The alkylbromide raw material is comprised principally of a mixture ofstraight chain and branched chain primary and secondary alkylbromides.By far the major portion of the alkylbromide raw material is straightchain primary alkylbromides making up from about to by weight of thealkylbromide raw material. A minor portion of the alkylbromide rawmaterial is a. mixture of from about 2% to about 5% by weight ofstraight chain secondary alkylbromide and from about 1% to about 4% of abranched chain primary alkylbromide. There can also be present in theraw material alkylbromide a very minor amount, i.e., less than 3% byweight, of an internal branched chain alkylbromide which is either asecondary or tertiary alkylbromide.

It is a significant discovery of the present invention that the straightchain secondary alkylbromides and the branched chain primaryalkylbromides which make up the minor portion of the alkylbromide rawmaterial have comparable reaction rates in the novel amination reaction.Thus, for example, it has been discovered that a compound such as2-bromododecane behaves more like l-bromo-Z-ethyl decane than likel-bromododecane in the amination reaction described herein.

It is this feature which, in part, led to the unexpected discovery thatan improved amination reaction required a time/temperature profile whichrepresented a major departure from time/temperature profiles of priorart amination reactions. FIGURES 1 and 2 illustrate that time/temperature profiles which characterize typical continuous and batchprocesses performed according to the present invention. The drawings aredeemed self-evident but it can be observed that each drawing shows twotemperature levels, the first being considerably lower than the second.The first relatively low curve represents the temperature prevailingduring the first reaction step, and the second elevated temperaturecurve represents the second reaction step. In both FIGURE 1 and FIGURE2, there is a sharp inclined line indicating the end of a typical firstreaction step and the initiation of a typical second reaction step. Thelimits and ranges both in time and temperature are critical, andalthough they have been mentioned above, they are described in moredetail below.

In addition to the foregoing specifically mentioned alkylbromides whichcomprise the alkylbromide raw material, there can also be present minoramounts of paratfins, unre'acted u-olefins, and the like at a level ofup to about 4% by Weight of the alkyl bromide without adverse effects.The a-olefins as well as the parafiins are essentially inert throughoutthe process and do not interfere wit-h the reaction.

The alkyl group of the alkylbromide reactant of the initial reactionmixture can contain from about to about 20 carbon atoms. In a preferredembodiment of the invention, the alkyl group contains from 12. to 16carbon atoms. These various chain length alkylbromides can be utilizedindividually per se or in combination with each other in any proportion.

Specific examples of suitable primary straight chain alkylbromides arethe following: l-bromodecane, l-bromoundecane, 1 bromododecane, 1bromotridecane, l-brornotetradecane, l-bromopentadecane,l-bromohexadecane, l-bromoheptadecane, l-bromooctadecane,l-bromononadecane and l-bromoeicosane. Specific examples of primarybranched chain alkylbromides which accompany such primary bromides asused in this process are: l-bromo-Z-ethyldecane, 1-bromo-2-butyloctane,l-bromo- 2-ethyldodecane, l-bromo-Z-butyldecane, 1-bromo-2-hexyloctane,l-bromo-Z-ethyltetradecane, l-bromo-Z-butyldodecane andl-bromo-Z-hexyldecane. Eaxrnplesof specific internal or secondarybromides which accompany such primary bromides as utilized in theprocess of this invention are 2-bromodecane, 2-bromoundecane,Z-bromododecane, 3 bromotridecane, 4 bromotetradecane,S-bromopentadecane, 2-bromohexadecane, 2-bromoheptadecane,2-bromo-3-bromohexadecane. The positioning of the bromine group can beon any of the carbons of the aliphatic chain. In addition, the moleculescan contain more than one atom of bromine.

The alkylbromide raw material employed in the amination process of thisinvention can be prepared, as mentioned above, by the reaction ofhydrogen bromides with unsaturated hydrocarbons, e. g., alpha-olefins.Ordinarily, if an unsymmetrical olefin is treated with hydrogen bromide,the hydrogen and the bromine add across the carbon-carbon double bond;the hydrogen attaches itself to the carbon atom bearing the greaternumber of hydrogen atoms and the bromine attaches itself to the carbonatom bearing the least number of hydrogen atoms. This mode of additionis termed the normal or Markownikoff addition, the product of which is asecondary bromide. The alkylbromide utilized in this invention should,as described above, contain a primary bromide as a major ingredient,e.g., 90% to 95% by weight. Primary bromides are formed by an additionprocess variously denoted as abnormal, anti-Markownikolf or free radicaladdition.

Several methods are known by which free radical addition can beeffected. Various free radical promoters such as peroxides, e.g.,hydrogen peroxide or acetyl peroxide, as Well as compounds which tend toform peroxides when contacted with unsaturated compounds such as oxygen,air, or ozone can be utilized with hydrogen bromide and an ot-olefin toetfect free radical or anti-Markownikolf addition. It is also known thatultraviolet radiations can be used to promote or catalyze the abnormaladdition of hydrogen bromide to unsaturated organic compounds. By suchprocesses as well as processes described in copending commonly-assignedapplications of Adrian Kessler, Ser. No. 333,575, and of Glen Wyness etal., Ser. No. 333,576, it is possible to produce alkylbromides for usein this invention which comprise a major portion of straight chainprimary alkylbromides and a minor amount of straight chain secondaryalkylbromides, and branch chain primary alklbromides.

Liquified dialkylamines utilized in this process have alkyl groupscontaining from 1 to about 3 carbon atoms. The two alkyl groups of theamine molecule can consist of the same or different numbers of carbonatoms within the specified range. The various amines, such as thoselisted below, can be used per se or in combination with each other inany amounts provided the essential molar proportions previouslymentioned are adhered to.

Specific examples of dialkylamines suitable for use in this inventionare the following: dimethylamine, diethylamine, dipropylamine,methylethylamine, methylpropylamine and ethylpropylamine. The preferreddialkylamine for this process is dimethylamine.

The following table illustrates several of the physical properties ofthe dialkylamines which are of importance in this invention.

TABLE I.-PHYSICAL PROPERTIES OF DIALKYLAMINES As can be seen from thepreceding table, some of the dialkylamines of this invention will not bein a liquified state at ordinary temperature and pressures. Others wouldbe volatilized at the temperatures utilized in this process unless thereaction takes place under suficient pressure to prevent saidvolatilization. It is also apparent from the preceding table that thispressure will vary with the particular amine utilized in the process.When dipropylamine is utilized in this process, a pressure as low as 75pounds per square inch gauge is sufiicient to maintain it in a liquifiedstate. A correspondingly higher pressure of above about 350 pounds persquare inch should be utilized in this process to maintain dimethylaminein a liquified state. The upper pressure limitation is governed only bythe strength of the reaction vessel and the amount of pressure that caneconomically be applied. Pressures over 3000 pounds per square inch are,however, not commercially feasible and this can be regarded as the upperlimit. When the preferred dimethylamine is utilized, the preferredpressure throughout the reaction system is maintained in the range offrom about 350 pounds per square inch gauge to about 1200 pounds persquare inch gauge. These pressures must be maintained throughout theentire process to prevent volatilization of the dialkylamines.

In this process, it has been found to be advantageous to use a molarexcess of liquified dialkylamine to react with the said alkylbromide toeffectively reduce formation of the quaternary ammonium compounds aswell as to insure almost complete reaction of the alkylbromide.

Molar ratios of dialkylamine to alkylbromide greater than about 8:1 havebeen found to be satisfactory in this process. At any molar ratio inexcess of about 8:1, the formation of quaternary ammonium compounds iseffectively reduced and the reaction is substantially complete. Theupper limitation on the molar excess is governed primarily by the sizeof the reactor and the desired output of the tertiary amine. However, ina preferred embodiment of this invention, a molar ratio of from 12:1 to18:1 is utilized.

Water is added as an essential ingredient to the reaction mixture incritical proportions. The addition of Water serves the useful purpose ofincreasing the reaction rate of the amination process. However, if anexcess of water is added to the dialkylamine and alkylbromide, twophases, an oil phase and a water phase, will form. Such a two-phasesystem substantially promotes the formation of the quaternary ammoniumcompounds and, thus, needs to be avoided. According to the process ofthe present invention, from about 5% to about 20% water by weight of thedialkylamine-water solution is utilized in this invention. In noinstance, however, should water be added to the reaction mixture in suchamounts as to form two phases as hereinbefore described. In a preferredembodiment of this invention, the water comprises from about 8% to aboutby weight of the dialkylamine-water solution.

In a preferred embodiment of the present invention, water is introducedinto the reaction mixture in the form of a dialkylamine-water solution.The dialkylamines are soluble in water to a high degree, whereas thealkylbromides are not. As a satisfactory alternative embodiment, each ofthe essential reaction components, i.e., alkylbromide, dialkylamine andwater, can be brought together separately into a mixing pump. Providedthat suflicient mixing is supplied and provided also that thedialkylamine and the alkylbromide are present in the requisite amounts,the reaction proceeds according to the contemplated method of thepresent invention.

The reaction mixture prepared according to the manner described above isthen heated to initiate the reaction between the alkylbromide and thedialkylamine. This is a highly exothermic reaction and the amount ofheat applied to the reaction system should take the factor intoconsideration. Actually, in this stage of the reaction it is principallythe straight chain primary alkylbromide ingredient which reacts with thedialkylamine to form the desired tertiary amine. This is so because thetemperature is held to a level in the range of from about 100 F. toabout 190 F., and in this temperature the rate of reaction of thestraight primary alkylbromide is considerably faster than either of theaforementioned minor alkylbromide components. Beginning with the initialheating at room temperature, e.g., of about 7080 F., this first reactionstage takes from about 2 to about 7 minutes. In a preferred embodiment,the reaction is conducted at a temperature in the range of from 120 F.to about 170 F. for a period of from about 3 to about 5 minutes, notcounting the time required to heat to that temperature range.

As pointed out previously, the reaction between the alkylbromide and thedialkylamine is highly exothermic. It may be necessary, therefore, toprovide the reaction system with a heat exchanger to aid in maintainingthe reaction temperature in the broad range of 100 F. to 190 F. andpreferably in the preferred range of 120 F. to about 170 F.

Strict caution must be exercised to prevent higher temperatures fromoccurring. Temperatures, for instance, in excess of about 190 initiatethe formation of undesirable quaternary ammonium compounds and perhapsalso tend to cause the formation of color bodies due to localizedoverheating in the system. The mean temperature in this initial reactionstage over the period of from about 2 to about 7 minutes is about 145 F.Within this period,

e.g., a maximum of about 7 minutes under the prescribed temperature andpressure (see herein-after), the reaction goes to from about tocompletion. This completion percentage corresponds to the amount ofstraight chain primary alkylbromide present as the major component.

\AS mentioned previously, one of the critical requirements of thepresent reaction system is maintaining a suflicient pressure within thesystem to keep the dialkylamine reactant as a liquid. As hereinbeforestated, these pressures can vary from a minimum of about 75 pounds persquare inch gauge up to any commercially feasible maximum. Preferredpressure limitations with the preferred dialkylamine, i.e.,dimethylamine, are from about 350 pounds per square inch gauge to about1,200 pounds per square inch gauge.

Under the conditions set forth above for the initial reaction, it isfound that the reaction product thereof comprises a major proportion oftrialkylamines due to the virtually complete conversion of the straightchain primary alkylbromide to the desired tertiary amine. The remainderof the reaction product is principally the as yet unreacted straightchain secondary alkylbromides, the branched chain primary'alkylbromides, dialkylamine, and water. In order to complete thereaction, the reaction product from the initial low temperature reactionis quickly heated to a temperature of from about 275 F. to about 375 F.and held there for -a period of from about 4.5 to about 12 minutes.Preferably, the temperature for this high temperature phase of thereaction should be from about 300 F. to about 350 F., and should lastfrom about 5 to about 9 minutes. By practicing the invention in thisway, it has surprisingly been discovered that the final reaction productcontains only negligible amounts of the undesired quaternary ammoniumcompounds. Moreover, there is provided yet another major unexpectedadvantage in that the amount of regenerated olefin is held to anabsolute minimum.

The interval between the completion of the first low temperaturereaction and the initiation of the high temperature reaction stageshould, as a practical matter, be as short as possible. No advantage isgained by interrupting the reaction at this point. In a continuousprocess, for instance, there need be no delay between these steps, thereaction product passing directly from one stage to the second stage.The high temperature needed for the second stage can be supplied by anymeans such as a heat exchanger 'or a heating water or steam jacket. In acontinuous process, a heat exchanger is a preferred embodiment, and in abatch reaction system, the reactor vessel can be surrounded with a hotwater or steam jacket.

At the conclusion of the second elevated temperature reaction stage, thereaction product is comprised predominantly of a desired tertiary amine,e.g., on the order of about 98 %-99%. This reaction product can bedirectly oxidized to yield an excellent highly effective amine oxidedetergent composition.

It should be noted that if temperatures on the order of 300 F. to 350 F.are employed in a single-stage amination reaction system, the reactionproduct will be seriously adulterated by the presence of regeneratedolefins, by quaternary ammonium compounds, as well as other undesiredby-products. Moreover, if the amination reaction is performed in asingle low temperature stage, the reaction will take a very inordinatelylong time and even then it will be subject to some of the samedisadvantages as a single-stage high temperature reaction.

The reaction product of the high temperature reaction step is comprisedof the following reaction products. The major ingredient, of course, isthe desired tertiary amine. Since the dialkylamine reactant is added inthe large molar excess described earlier, there is still unreacteddialkylamine remaining. Hydrogen bromide is formed as a by productduring the reaction between the alkylbromide and the dialkylamine. Thehydrogen bromide forms a salt with the available excess dialkylamine andis present in that form. Besides these reaction products there can bepresent in varying but always minor amounts of unreacted alkylbromide,regenerated olefin, and vinylidene branched olefins.

Separation of the desired tertiary amine reaction product can beperformed in any devised manner. While not an essential step of thepresent invention, recovery of the tertiary amine is usually performedby adding a slight excess of sodium hydroxide to the final reactionprodnot. This results in the formation of a brine solution which is thenpassed to a distillation column where the diallaylamine is stripped 01f.One convenient way of doing this is by passing steam through the brinesolution. The stripped off dialkyla'mine can be recycled back to thefirst step of the reaction.

The remaining reaction product is allowed to stand under pressure for aperiod of time. Two phases gradually appear; the lower phase isessentially trialkyl amines and the upper phase is essentially sodiumbromide and water. These phases are easily separated and the sodiumbromide is recovered and the water is discarded. The phase containingthe tertiary amines is distilled. The distillate is the water-whitetrialkyl amine.

It is desirable throughout the reaction system to provide for goodmixing of the reactants and the reaction mixture. This is especiallytrue in the initial low temperature reaction, but it is desirable alsoin the second or high temperature reaction.

The process of this invention can be accomplished in both batch andcontinuous processes. In both cases, however, the particular reactionvessel utilized must be capable of withstanding relatively highpressures and must be capable of effecting a two-step temperaturereaction as related above. Furthermore, the batch reaction vessel mustbe equipped with an agitating device to eifect the good mixing which, asmentioned above, is desirable. Suitable reaction vessels for the processof this invention are generally described in Perrys Chemical EngineersHandbook (3rd edition, 1950), at pages l2561258.

The following specific examples are given in order to further explainand illustrate this invention. They are not intended to limit the scopein any way.

EXAMPLE I The reaction vessel utilized in this example of the aboverelated process was a tubular reactor. The major component of thereactor was a schedule 80 stainless steel pipe of three-quarter inchnominal inside diameter which was 500 feet long. One heat exchanger wasprovided which permitted gradual heating of the reaction components inthe first 100 feet of the reactor. Another heat exchanger was located at200 feet from the reactor inlet. This heat exchanger permitted rapidheating of the reaction components and products. The entire system wasinsulated to prevent major heat losses.

Water was continuously metered into a dimethylamine stream so as to forma dimethylamine-water solution containing by weight of water. Thedimethylamine-water mixture was then metered into an alkylbromide streamat a molar ratio of dimethylamine to alkylbromide of 17.8:1. Thealkylbromide was comprised by weight of 88.8% primary straight chainalkylbromides, i.e., 57.6% l-bromododecane, 22.3% 1brom0tetradecane and8.9 l-bromohexadecane, 3.5% branched chain primary alkylbromides, 5%straight chain secondary alkylbromides, 1.7% paraffins and 1.0a-olefins. The chain length of the alkyl groups in the alkyl bromidereactant was a mixture of 12, 14 and 16 carbon atoms.

This mixture was introduced into the above-described tubular reactor andheated until the temperature rose to 178 F. The reaction mixture was ina temperature range of 100 F. to 178 F. for about 2.7 minutes. It wasmaintained at 178 F. for 1.6 minutes. At this point, the temperature ofthe mixture was abruptly raised to 303 F.

and held there for 4.8 minutes, after which the temperature was againreduced to room temperature.

Throughout the entire reaction, a pressureof about 1000 pounds persquare inch was applied to the system to keep the various components inthe liquid state. Mild agitation occurred throughout the tubularreactor.

The yield of desired tertiary amine alkyldimethylamine was over basedupon the alkylbromide feed stream. The yield of dialkyldimethylquaternary ammonium bromide impurity was only 0.17% by weight of thetotal reaction product.

EXAMPLE II In this example, a reaction vessel similar to that describedin Example I was utilized.

Water was continuously metered into a dimethylamine stream so as to forma dimethylamine-water solution containing 13% by Weight of water. Thedimethylaminewater mixture was then metered into an alkylbromide streamat a molar ratio of dimethylamine to alkylbromide of 13:1. Thealkylbromide had the same chain length distribution as in Example Iabove and was comprised by weight of 88.8% primary straight chainalkylbromides, i.e., 57.6% l-bromododecane, 22.3% l-bromotetradecane and8.9% l-bromohexadecane, 3.5% branched chain primary alkylbromides, 5%straight chain secondary alkylbromides, 1.7% paraffins and 1.0%a-olefins.

This mixture was introduced into the above-described tubular reactor.During the first 3.2 minutes the temperature was gradually raised from80 F. to 178 F. The temperature was in a range of F. to 178 F. for about2.7 minutes. At this point, the temperature was abruptly raised to 326F. and held there for 4.8 minutes, after which the temperature wasreduced to room temperature.

The yield of dialkyldimethyl quaternary ammonium bromide impurity wasonly 0.13% by weight of the total reaction product. The yield of thedesired alkyldiniethylamine product was over 95.5 based upon thealkylbromide feed stream.

EXAMPLE III The reactor described in Example I was utilized for thefollowing runs.

In all of the following runs, a mixture of alkylbromide, dimethylamineand water was prepared. The alkylbromide in all runs was comprised byweight of 93.2% primary straight chain alkylbromides, i.e. 57.2% 1-bromododecane, 22.3% l-bromotetradecane and 8.9% 1- bromohexadecane,3.5% primary branched chain alkylbromides, 5% secondary alkylbromides,1.7% parafiins and 1.0% a-olefins.

This mixture was introduced into the abovedescribed tubular reactor.During the first 3.2 minutes, the temperature was gradually raised from80 F. to 178 F. At this point, the temperature was abruptly raised to326 F. and held there for 4.8 minutes, after which the temperature wasreduced to room temperature.

The yield of dialkyldimethyl quaternary ammonium bromide was only 0.13%by weight of the total reaction product. The yield of alkyldimethylaminewas over 95.5% based upon the alkylbromide feed stream.

EXAMPLE IV The reactor described in Example I was utilized for thefollowing runs.

In all of the following runs, a mixture of alkylbromide (the alkyl groupbeing a mixture of C to C carbon atoms, predominantly C to Cdimethylamine and water was prepared. The alkylbromide in all runs wascomprised by weight of 93.2% straight chain primary alkylbromides, 2.5%branched chain primary alkylbromides, 3% secondary alkylbromides, 1.2%parafiins and 0.1% a-olefins. The procedure followed in Example I wasfollowed herein. The results of four runs are tabulated below.

It takes about .5 minute to get from room temperature to 100 F.

Temperatures in (3) in the above table are part Of initial reaction ofthe heretofore discussed process. Temperature Shown in (5) above arerepresentative of the second stage of the process.

In all cases, excellent results were obtained. As can be seen from Table1, the highest incidence of dialkyldimethyl ammonium bromide impuritywas 0.52%. In all cases, over 95% of the reaction product Was desiredtrialkylamines.

EXAMPLE V The reaction vessel utilized in this example was a 1- gallonbatch reaction vessel capable of withstanding a pressure up to 1,000pounds per square inch gauge. This reaction vessel was fitted with astirring device and thermometer.

The dimethylamine-water solution containing the percentages of watershown in Table 2 were placed in the reactor and heated to thetemperature specified in the table below. Alkylbromide (the alkyl groupbeing a mixtur of C to C carbon atoms, predominantly C to C comprised byweight of 93.2% primary straight chain alkylbromide, 2.5% primarybranched chain alkylbromides, 3% secondary alkylbromide, 1.2% paraflinsand 0.1% a-olefins, was heated outside the reactor and injected into thebatch reactor in the hereinafter stated mol ratio of dimethylamine toalkylbromide. The reaction was allowed to proceed under nearly adiabaticconditions under which the temperature of the reaction stabilized. Thetemperature was then increased to 300 F. for 9 minutes.

As can be seen from the above table, the percentage ofdialkyldimethylammonium bromide was in all cases less than 0.40%. Over95% of the reaction product was trialkylamine.

In the foregoing examples, other of the alkylbromides and dialkylamines,e.g., diethylamine, in the respective ranges hereinbefore mentioned, canbe substituted for the ones specifically mentioned. Additionally, theamounts of each component can be varied within the ranges delineated inthe foregoing discussion. Likewise, the residence time in the reactorand the temperature of the reaction can be varied within the limitsdiscussed previously.

The foregoing description of the invention has been presented describingcertain operable and preferred embodiments. It is not intended that theinvention should be so limited since variations and modificationsthereof will be obvious to those skilled in the art, all of which arewithin the spirit and scope of this invention.

What is claimed is:

1. A process for preparing trialkylamines comprising the steps of (l)preparing a reaction mixture containing an alkylbromide, saidalkylbromide comprised of a major proportion of straight chain primaryalkylbromides and a minor portion of straight chain secondary andbranched-chain primary alkylbromides wherein the alkyl group of saidalkylbromides contains from about 10 to about 20 carbon atoms; and adialkylamine-water solution comprising a dialkylamine wherein the alkylgroups contain from 1 to about 3 crabon atoms; said dialkylamine-watersolution containing from about 5% to about 20% water by weight; themolar ratio of said dialkylamine to said alkylbromide in said reactionmixture being in excess of about 8:1;

(2) reacting said alkylbromide with said dialkylamine for from about 2to about 7 minutes at a temperature of from about F. to about 190 F. andunder sufficient pressure to maintain said dialkylamine in a liquifiedstate to form a reaction product;

(3) thereafter heating said reaction product to a reaction temperatureof from about 275 F. to about 375 F. for from about 4.5 to about 12minutes and under sufiicient pressure to maintain the dialkylamine in aliquified state.

2. The process of claim 1 wherein the molar ratio of dialkylamine toalkylbromide is from 12:1 to 18:1.

3. The process of claim 1 wherein said dialkylaminewater solutioncontains from about 8% to about 15% water by weight.

4. The process of claim 1 wherein the alkyl group of the saidalkylbromide contains from about 12 to about 16 carbon atoms.

5. The process of claim 1 wherein the residence time in step 2 is fromabout 3 to about 5 minutes at a temperature of from about F. to about F.and the residence time in step 3 is from about 5 to about 9 minutes at atemperature of from about 300 F. to about 350 F.

6. The process of claim 1 wherein the dialkylamine is dimethylamine.

7. The process of claim 5 wherein a pressure of from about 350 to about1200 pounds per square inch gauge is applied to the system.

No references cited.

CHARLES B. PARKER, Primary Examiner.

R. L. RAYMOND, Assistant Examiner.

